The remaining charges authorize a maximum penalty of life in prison or a fixed term of years.

The indictment includes many of the same weapon-of-mass-destruction charges, punishable by the death penalty, that were brought against the 19-year-old Tsarnaev in April.

But prosecutors added charges covering the slaying of an MIT police officer and the carjacking of a motorist during the getaway attempt that left Tsarnaev’s older brother, Tamerlan, dead.

"I have met with several of those injured in the bombing and the family of those deceased. I was able to discuss the process moving forward and learn about them personally,” U.S. Attorney Carmen Ortiz said in a press conference Thursday. "Their strength is extraordinary and we will do everything we can to pursue justice.”

Ortiz said whether or not the prosecution will seek the death penalty is up to U.S. Attorney General Eric Holder.

Rick DesLauriers Special Agent in Charge of the FBI Boston office thanked investigators for their work on the case.

"The victims will always be in our hearts, thoughts and prayers,” he said. "We’re delighted justice is being served for the victims and their families.”

State Police Col. Timothy Alben called Thursday’s indictment the "second step” in the case and said more work will come in the coming months.

The indictment alleges Tsarnaev and his brother Tamerlan Tsarnaev conspired to use improvised explosive devices to kill and maim as many people as possible at the Boston Marathon.

The two bombs, made from pressure cookers, detonated seconds apart, killing three people and injuring hundreds.

The indictment details the days that followed the bombing, culminating in the death of Tamerlan Tsarnaev in a violent shootout with police and the eventual capture of Dzhokhar in Watertown.

According to the indictment, while hiding in a drydocked boat in Watertown, Dzhokhar Tsarnaev wrote the following messages on the inside wall of the boat:

"The U.S. government is killing innocent civilians;” "I can’t stand to see such evil go unpunished;” "We Muslims are one body, you hurt one you hurt us all;” "Now, I don’t like killing innocent people. It is forbidden in Islam but due to said [unintelligible] it is allowed;”

"Stop killing our innocent people and we will stop.” Ortiz would not comment further on Tsarnaev’s writings or whether they are considered a confession.

The Tsarnaev brothers had roots in the turbulent Russian regions of Dagestan and Chechnya, which have become recruiting grounds for Islamic extremists. They had been living in the U.S. about a decade.

But the indictment made no mention of any larger conspiracy beyond the brothers, and no mention of any direct overseas contacts with extremists.

During Thursday’s press conference, Ortiz said they believe the attacks were protests against the United States for perceived injustices against Muslims.

The indictment also suggests the Internet played a central role in the suspects’ radicalization.

The papers detail how, after using the Internet to study jihad propaganda and bomb-making instructions, the brothers placed knapsacks containing the shrapnel-packed pressure-cooker bombs near the finish line of the 26.2-mile race.

The court papers also confirm that Dzhokhar Tsarnaev inadvertently contributed to his brother’s death by running him over during a shootout with police.

Tsarnaev is scheduled to be arraigned July 10, in U.S. District Court in Boston.